Sample Preparation 

Soil: 

The volume/weight of soil needed to complete various soil analysis is dependent on the number and type of analysis desired. The weight/volume of a soil sample collected using accepted field sampling techniques is much greater than is necessary to complete all standard analyses. Samples are relatively large because multiple soil cores have to be taken throughout the field and combined to form one sample. A volume of about 250 cc of moist soil is sufficient to complete all standard laboratory analyses. The minimum weight of soil needed to complete selected analysis can be found in the table below. 

Soil samples submitted to the STAR laboratory should be air dried at a temperature of 25o to 35oC. Soil samples should not be oven dried. After drying, soils should be ground to pass a 2 mm sieve. A dried sample of 50 grams is sufficient to complete all standard analyses. Each sample should be packaged securely and labeled clearly. Each sample set should include a listing of sample numbers, PI or project name, and date. A convenient container for the dried ground samples are 3X5" paper coin envelopes. Do not seal the envelopes, use a paper clip to hold closed.

Soilless Mix: 

Soilless mix samples should be submitted as collected in a sealed plastic bag. A 500 cc volume of sample is sufficient to complete all standard analyses. Each sample should be packaged securely and clearly labeled. Each sample set should include a listing of sample numbers, PI or project name, and date.

Compost, Manure, and Sludge: 

Compost, manure, and sludge samples should be submitted as collected in a sealed plastic bag. Liquid samples should be submitted in large mouth containers.  A minimum volume of 500 cc's of sample is required to complete all standard analyses. Each sample should be packaged securely and clearly labeled. Each sample set should include a listing of sample numbers, PI or project name, and date. Please select a container size large enough to allow for mixing of the sample in the container.

Plant Tissue: 

The amount of plant tissue currently needed to analyze for elemental constituents is less than 2 grams.

Plant tissue samples should be dried at approximately 60o C in a forced air oven. All tissue samples must be ground to pass a 2 mm sieve. A 5 gram samples is desired to complete all analyses. Smaller samples should be ground more finely to assure that a homogeneous sample can be weighed accurately. Samples should be placed in a 3X5" paper coin envelop and clearly labeled. Each sample set should include a listing of sample numbers, PI or project name, and date.  It is recommended that paper coin envelopes be used so that the sample can be redried in our drying oven prior to sample analysis. Do not seal the envelopes, use a paper clip to hold closed. 
 

Feed: 

Feed samples that require Dry Matter analysis should be place in a plastic bags and sealed. A 50 gram sample is sufficient to analyzed for Dry Matter and all other analyses.

Feed samples not requiring Dry Matter analysis should be dried at approximately 65o C in a forced air oven. Feed samples should be ground to pass a 2 mm sieve. A 20 gram samples is sufficient to complete all analyses. Samples should be placed in a 3X5" paper coin envelop and clearly labeled. Each sample set should include a listing of sample numbers, PI or project name, and date. It is recommended that paper coin envelopes be used so that the sample can be redried in our drying oven prior to sample analysis. Do not seal the envelopes, use a paper clip to hold closed.

Water:

A 250 ml sample volume is sufficient to complete all water analyses. Samples should be placed in acid washed plastic bottles which have been thoroughly rinsed with deionized water and if possible rinsed with the sample. Sample containers should be labeled clearly using water resistant marker. Each sample set should include a listing of sample numbers, PI or project name, and date. All water samples should be stored in refrigerated compartments maintained at 4oC + 5oC until submitted for analysis.

Water samples can be separated into different preparation types according to the desired analyses. 

• Raw Unacidified(RU), which is a completely untreated sample. The RU sample can be analyzed for any of the analyses available.

• Raw Acidified(RA) is a RU sample that has 2.5 % Nitric Acid added by volume. The RA samples can be analyzed to determine Total
  Dissolved Metals. The sample is filtered through a 0.45 um membrane filter prior to ICP analysis.

• Filtered Unacidified(FU) samples are RU samples which are filtered through a 0.45 um membrane but not acidified. This sample type is used to determine pH, conductivity, alkalinity, acidity, anion content and residue of evaporation.

• Filtered Acidified(FA) samples are FU samples with 2.5% Nitric acid by volume. Dissolved metal are determined on FA samples by ICP.
   

Water samples requiring ICP analysis only are considered Filtered Acidified samples. Each sample should be filtered through a 0.45µm filter membrane. Samples should be acidified  with Nitric acid and securely capped. A 2% acid concentration is sufficient to hold elements in solution.  Sample volume should be at least 10 ml for ICP analysis.